CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
CURRENT ASSETS:
Cash and cash equivalents	$ 18,392	$ 19,064
Marketable securities	40,260	75,135
Accounts receivable, net	290	617
Inventories, net	4,913	4,553
Prepaid and other current assets	3,297	6,181
Total current assets	67,152	105,550
Right-of-use assets	14,749	15,502
Property and equipment, net	7,783	7,665
Restricted cash	0	2,150
Other noncurrent assets	6,235	2,473
Total assets	95,919	133,340
CURRENT LIABILITIES:
Accounts payable	3,520	3,218
Accrued expenses and other current liabilities	9,020	9,764
Contract liabilities	150	987
Convertible notes	1,641	8,594
Total current liabilities	14,331	22,563
Operating lease liabilities, noncurrent	15,888	16,681
Other noncurrent liabilities	44	126
Total liabilities	30,263	39,370
COMMITMENTS AND CONTINGENCIES (Note 16)
STOCKHOLDERS’ EQUITY:
Preferred stock—$0.0001 par value: 1,000,000 shares authorized; no shares issued and outstanding	0	0
Common stock—$0.0001 par value: 600,000,000 shares authorized; 181,420,313 and 163,099,124 shares issued and outstanding at June 30, 2023 and December 31, 2022	18	16
Additional paid-in capital	358,833	345,742
Accumulated other comprehensive loss	(390)	(1,279)
Accumulated deficit	(292,805)	(250,509)
Total stockholders’ equity	65,656	93,970
Total liabilities and stockholders’ equity	$ 95,919	$ 133,340